Anti-cancer compounds

ABSTRACT

The invention provides bradykinin antagonists and pharmaceutically acceptable salts thereof having anti-cancer activity. These anti-cancer compounds are particularly useful for inhibiting the growth of lung and prostate cancers.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation in part of U.S. patent application Ser. No. 10/035,662, filed Dec. 28, 2001, now U.S. Pat. No. 7,071,168, which is a continuation of U.S. patent application Ser. No. 09/378,019, filed Aug. 19, 1999, now U.S. Pat. No. 6,388,054, which claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 60/141,169 filed Jun. 25, 1999. These priority documents are incorporated herein in their entirety by this reference.

GOVERNMENT INTEREST

This invention was made with Government support under grant numbers HL-26284 awarded by the National Heart, Lung and Blood institute and CA-78154 awarded by the National Cancer Institute of the U.S. National Institutes of Health. The Government has certain rights in this invention.

REFERENCE TO SEQUENCE LISTING

This application contains a Sequence Listing submitted as an electronic text file named “2848-41-CON-CIP_ST25.txt”, having a size in bytes of 1kb, and created on 20 Dec. 2007. The information contained in this electronic file is hereby incorporated by reference in its entirety pursuant to 37 CFR §1.52(e)(5).

FIELD OF THE INVENTION

The invention relates to anti-cancer compounds and methods of making and using these compounds.

BACKGROUND OF THE INVENTION

Many lung and prostate cancers, of which small cell lung cancer (SCLC) is a prime example, have a neuroendocrine phenotype, and their growth is stimulated by neuropeptides. Antagonists of several peptides (e.g. bradykinin, substance P, bombesin) have been used in experimental treatment of models of SCLC in animals. Among the most potent of the peptides examined thus far, crosslinked dimers of bradykinin antagonist peptides have been efficacious both in vitro and in vivo against strains of SCLC and other tumors (Chan et al., Immunopharmacology 33: 201-204, 1996; Stewart et al., Can. J. Physiol. Pharmacol. 75: 719-724, 1997; Stewart et al., U.S. Pat. No. 5,849,863). Prostate cancers show a similar neuroendocrine phenotype and are susceptible to these neuropeptide antagonists.

Bradykinin (BK: Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg (SEQ ID NO: 1) is an important growth factor for many types of cancers. Many cancers express receptors for BK and overproduce BK to stimulate their growth. In addition to direct stimulation of cancer growth, BK stimulates angiogenesis in solid tumors by stimulating release of vascular endothelial growth factor (VEGF) and facilitates tumor spreading and invasion by stimulating release of matrix metalloproteases (MMPs). Thus, antagonists of BK have three potential tumor-inhibiting activities.

The first BK antagonists developed were peptides which did not show any anti-cancer activity. Thereafter, several non-peptide BK antagonists were reported from several laboratories (Inamura et al., Can. J. Physiol. Pharmacol. 75: 622-628, 1997). The present inventors also discovered a group of acylated amino acid amides having BK antagonist activity that are also potent anti-cancer agents (see U.S. Pat. No. 6,388,054). Following the discovery that certain dimerized bradykinin antagonist peptides are cytotoxic for cancer cells and inhibit tumor growth, interest grew in finding smaller, non-peptide BK antagonists with similar anti-cancer efficacy but lower cost of synthesis as well as the possibility non-parenteral routes of administration.

SUMMARY OF THE INVENTION

The present invention provides anti-cancer agents comprised of a range of novel acyl amino acid amide derivatives having BK antagonist activity and having the ability to inhibit growth of small cell lung cancer (SCLC), non-small cell lung cancer (NSCLC) and prostate cancer (PC) cells in standard in vitro tests as well as to inhibit growth of these cancers in vivo in tumors implanted subcutaneously in athymic nude mice. The anti-cancer agents in this application are derivatives of compound M570, which has the chemical structure: Pentafluorocinnamoyl-O-(2,6-dichlorobenzyl)tyrosine-4-amino-2,2,6,6-tetramethylpiperidine (Abbreviated F5C—OC2Y-Atmp).

M570 was disclosed in U.S. Pat. No. 6,388,054, and is a potent inhibitor of SCLC, NSCLC and PC growth, both in vitro and in vivo. The compounds of the present invention were obtained by replacement of one or two of the three functional groups in M570 to produce more potent anti-cancer compounds that are advantageously more soluble and may preferably be administered orally.

The present invention also provides methods of inhibiting cancer growth by administering to a subject afflicted with cancer a therapeutically effective amount of one or more of the compounds of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Non-peptide compounds have recently been described as antagonists for a variety of peptide hormones, including bradykinin. Such peptide mimetics are pharmaceutically desirable, as they are more likely to be orally available and are less likely to be susceptible to enzymatic degradation. Although there are few guidelines to direct a search for such compounds, the present inventors synthesized various molecules containing the presumed requisite hydrophobic and basic groups and examined these compounds for anti-bradykinin and anti-cancer activity. Several potent anti-cancer compounds were found in this search.

Anti-cancer activity was determined on cultured human cancer cell lines using the standard tetrazolium (MTT) assay and in human cancers implanted subcutaneously in athymic nude mice. Potent compounds were found to stimulate apoptosis in SCLC cells. They inhibited implanted tumors by inhibiting growth directly, by inhibiting neovascularization and by inhibiting matrix metalloproteases, which are important for tumor extension and migration.

The anti-cancer compounds of the present invention have the chemical formula: A-B-R  (Formula I) wherein,

A is an acylating group, and preferably a hydrophobic acylating group, or an anti-inflammatory substituent;

B is an amino acid or substituted amino acid; and,

R is a substituted amide, preferably having additional polar character.

Abbreviations of the chemical entities that compose the anti-cancer compounds of the present invention that are used in this disclosure are listed in Table 1.

With reference to Table 1, the group A acylating groups may be chosen from: Aaa, Aba, Aca, Acrc, Aic, Amts, 6Ani, Aq2c, Arac, Aspr, Atfb, 4Atfb, B6, B6P, Baaa, Bbz, Bcin, Bcpa, Bcpoa, Biot, Bipa, 4Bpc, Bphs, tBua, Bzac, Chbu, Chc, CHFB, Chl, Chpa, 2Cln, Cmioc, Cpcpc, Dbhc, Dca, Dcla, tDecl, Dfc, Dhq, Dmc, Dmo, 22Dp, Esul, 2-Fa, 3-Fa, F5b, F5bs, F5bz, F3c, F5c, Fcin, aFcn, Fmoc, F5pa, Fmpi, F5po, F5pt, Gbz, Hcn, Hmqc, Hor, 2Hyb, 3Iac, 3Ibu, 2Ina, Indo, Inp, Ktlc, Ktpf, Mca, aMcn, Mcoa, 34Mdc, MTPA, 1Nac, 1Nala, Nap, Napr, Nba, Octe, Otac, Pac, Pas, Pcin, Pcn, Pcnl, βPhc, 3Php, 5Phv, Pic, Piva, Ppr, Ptmb, αPtpa, Pya, Pyrc, Pyz, 13cR, Ret, Rio, Saa, Sab, cSdc, Sibu, cSsa, tβSts, Taa, Tchc, Tcpa, Tf2c, 4Tfmb, Thia, Th2n, Tic, Tmb, 4Tmbs, Tmbz, Tmcc, or ZPcn.

Group A anti-inflammatory substitutents may include indomethacin (Indo), aspirin (Aspr), naproxen (Napr), diclofenac (Dfc), ketoprofen (Ktpf) or ketorolac (Ktlc). Because solid tumors are surrounded by a zone of inflammation, anti-cancer analogs having the F5C moiety of M570 replaced by non-steroidal anti-inflammatory drugs (NSAIDS) were synthesized. Although standard NSAIDS are typically administered as free acids, esters or amides of these are also effective. Some of these anti-inflammatory compounds are potent anti-cancer agents in their own right. Combined in the structure of the anti-cancer bradykinin antagonists of the present invention, the resulting compounds are particularly effective anti-cancer agents.

Group B amino acids may be chosen from: Bip, Ddip, F5F, F3MF, hPhe, MC2Y, Nal, NMF, OBPY, OBrZY, OC2Y, OCIY, Pal, PBF, PCNF, PFF, PIF, PNF, Tic, or Tyr(Bzl).

Group R amide groups may be chosen from: Abzp, Aem, Alp, Ambi, Apia, Apyr, AquR, Atmp, BapR, BapS, Bdbh, Bhp, Btmb, Cbp, Chmp, tCip, 4Clbp, Cpp, Cypp, Daep, Dasd, Dcpp, cDmap, cDmbp, cDmm, Dmmp, Dmpz, Dpic, Fbhp, 4Fbp, Fpmp, Fpdh, Matp, 4Mbp, Mpz, Ocp, Pep, Pipe, Pipp, Pipz, Pmpz, Ppp, Pypz, 3Qum, or Tmbp.

TABLE 1 Abbreviations for Chemical Groups Used to Synthesize the Anti-Cancer Compounds of the Present Invention Aaa = 1-Adamantaneacetyl Aba = 2-cis-4-trans-Abscisic acid Abzp = 4-Amino-1-benzylpiperidine Aca = 1-Adamantanecarboxyl Acrc = Acridine-9-carboxyl Aem = 4-(2-Aminoethyl)-morpholine Aic = 2-Aminoindane-2-carboxylic acid Alp = 1-Allylpiperazine Ambi = 2-(Aminomethyl)benzimidazole Amp = 1-(3-Aminopropyl)-4-methylpiperazine Amts = 2-Acetamido-4-methyl-5-thiazolesulfonyl 6Ani = 6-Aminonicotinoyl Apia = 1-(3-Aminopropyl)imidazole Apyr = 3-Amino-pyrrolidine Aq2c = Anthraquinone-2-carboxyl AquR = (R)-(+)-3-Aminoquinuclidine Arac = Arachidonyl Aspr = O-Acetylsalicyl: 2-acetoxybenzoyl Atfb = 3-Amino-2,5,6-trifluorobenzoyl 4Atfb = 4-Amino-2,3,5,6-tetrafluorobenzoyl Atmp = 4-Amino-2,2,6,6-tetramethylpiperidine AtmpO = 4-Amino-2,2,6,6-tetramethylpiperidinyloxy B6 = 3-Hydroxy-5-(hydroxymethyl)-2-methyl-4-pyridylmethyl (Vitamin B6, Pyridoxamine) B6P = 3-Hydroxy-5-(hydroxymethyl)-2-methyl-4-pyridylmethyl- 5-phosphate Baaa = 2,2-Bis(acrylamido)acetyl BapR = (R)-(−)-1-Benzyl-3-aminopyrrolidine BapS = (S)-(+)-1-Benzyl-3-aminopyrrolidine Bbz = 4-Boronobenzoyl Bcin = 4-Boronocinnamoyl Bcpa = bis(4-Chlorophenyl)acetyl Bcpoa = bis(4-Chlorophenoxy)acetyl Bdbh = (1S,4S)-(+)-2-Benzyl-2,5-diazabicyclo[2.2.1]heptane Bhp = 1-Benzylhomopiperazine Biot = Biotinyl Bip = β-(4-Biphenylyl)alanine Bipa = 4-Biphenylacetyl 4Bpc = 4-Biphenylcarboxyl Bphs = 4-Biphenylsulphonyl Btmb = 3,5-Bis(trifluoromethyl)benzylamine tBua = tert-Butylacetyl Bzac = 3-Benzoylacryloyl Cbp = 1-(4-Chlorobenzhydrylpiperazine) 2Ccn = 2-Chlorocinnamoyl Chbu = 2-Cyclohexylbutyryl Chc = α-Cyano-4-hydroxycinnamoyl CHFB = 4-Carboxy-hexafluorobutyryl Chl = Chlorambucil: 4-[p-(bis[2-Chloroethyl]amino)- phenyl]butyryl Chmp = 1-Cyclohexylmethylpiperazine Chpa = α-Cyclohexylphenylacetyl tCip = trans-1-Cinnamylpiperazine 4-Clbp = 1-(4-Chlorobenzyl)piperazine 2Cln = 2-Chloronicotinoyl Cmioc = 3-(2-Chlorophenyl)-5-methylisoxazole-4-carbonyl Cpcpc = 1-(4-Chlorophenyl)-1-cyclopropanecarboxyl Cpp = 1-(4-Chlorophenyl)piperazine Cypp = 1-(4-Cyanophenyl)piperazine Daep = 1-(2-(Diallylamino)ethyl)piperazine Dasd = 1,4-Dioxa-8-azaspiro[4.5]decane Dbhc = 3,6-Di-tert-butyl-4-hydroxycinnamoyl Dca = Dicyclohexylacetyl Dcla = Dichloroacetyl Dcpp = 1-(2,3-dichlorophenyl)piperazine tDecl = trans-4-(Diethylamino)cinnamyl Dfc = Diclofenac: 2-[(2,6-Dichlorophenyl)amino]phenylacetyl Dhq = 2,3-Dehydroquinuclidine-3-carboxyl Dip = 3,3-Diphenylalanine cDmap = cis-2,6-Dimethyl-1-allyl-piperazine cDmbp = cis-2,6-Dimethyl-1-benzylpiperazine Dmc = Dimethoxycinnamoyl CDmm = cis-2,6-Dimethylmorpholine Dmmp = cis-2,6-Dimethyl-1-(methoxycarbonylmethyl)piperazine) Dmo = 3,7-Dimethyl-6-octenoyl: R-+-Citronellyl Dmpz = 2,6-Dimethylpiperazine 22Dp = 2,2-Diphenylpropionyl Dpic = Di-(2-picoyl)amine Esul = Exisulindacyl: (Z)-5-Fluoro-2-methyl-[[4- (methylsulfonyl)phenyl]methylene]-1H-indene-3-acetyl; (cis) 2-Fa = 2-Furanacryloyl 3-Fa = trans-3-Furanacryloyl F5b = 2,3,4,5,6-Pentafluorobenzyl Fbhp = 1-(4-Fluorobenzyl)homopiperazine 4-Fbp = 1-(4-Fluorobenzyl)piperazine F5bs = Pentafluorobenzenesulfonyl F5bz = Pentafluorobenzoyl F3c = 2,3,5-Trifluorocinnamoyl F5c = 2,3,4,5,6-Pentafluorocinnamoyl Fcin = 4-Formylcinnamoyl αFcn = αFluorocinnamoyl F5F = Pentafluorophenylalanine F3MF = 4-Trifluoromethylphenylalanine Fmoc = 9-Fluorenylmethoxycarbonyl F5pa = 2,3,4,5,6-Pentafluorophenylacetyl Fpmp = 1-bis(4-Fluorophenyl)methylpiperazine Fmpi = (Z)-5-Fluoro-2-methyl-(4-pyridylidene)-3-indenylacetyl F5po = 2,3,4,5,6-Pentafluorophenoxyacetyl F5Pt = Pentafluorophenylthiocarbamyl Fpdh = (1S,4S)-(−)-2-(4-Fluorophenyl)-2,5- diazabicyclo[2.2.1]heptane Gbz = 4-Guanidinobenzoyl Gun = Guanidyl Hcn = 9-(N-Hydroxycarbamoyl)-nonanoyl Hmqc = 3-Hydroxy-2-methyl-4-quinolinecarboxyl Hor = (S)-(+)-Hydroorotic acid HPhe= Homo-phenylalanine 2Hyb = 2-Hydroxybenzoyl 3Iac = 3-β-Indoleacryloyl 3Ibu = Indole-3-butyryl Igl = α-2-Indanylglycine 2Ina = 2-Indanylacetyl Indo = Indomethacin: 1-[p-Chlorobenzoyl]-5-methoxy-2- methylindole-3acetyl Inp = Isonipecotic acid: hexahydroisonicotinic Isoquinolineacetyl Ktlc = Ketorolac: (±)5-benzoyl-2,3dihydro-1H-pyrrolizine-1- carboxyl: Toradol Ktpf = Ketoprofen: 2-(3-benzoylphenyl)propionyl Matp = 4-(Methylamino)-2,2,6,6-tetramethylpiperidine 4-Mbp = 1-(4-Methylbenzyl)piperazine Mca = 2-Methylcinnamoyl αMcn = α-Methylcinnamoyl Mcoa = 7-Methoxycoumarin-4-acetyl MC2Y = N-Methyl-O-2,6-dichlorobenzyl-tyrosine 34Mdc = 3,4-(methylenedioxy)cinnamoyl Mpz = 1-Methylpiperazine MTPA = α-Methoxy-α-trifluoromethylphenylacetyl 1Nac = 3-(1-Naphthyl)acryloyl Nal = β-Naphthylalanine 1Nala = Naphthylacetyl Nap = Naphthoyl Napr = Naproxen: 6-Methoxy-α-methyl-2-Naphthaleneacetyl Nba = Norbornane-2-acetyl Nif = Niflumic acid, 2-(3-[Trifluoromethyl]aniline)nicotinic acid NMF = N-Methylphenylalanine OBPY = O-Benzyl-phosphotyrosine OBrZY = (O-2-Bromo-Cbz)-tyrosine OCIY = O-2,6-Dichlorobenzyl-3,5-diiodo-tyrosine OC2Y = O-2,6-dichlorobenzyl tyrosine Ocp = 1-Octylpiperazine Octe = 2-Octenoyl Otac = (−)-2-Oxo-4-thiazolidinecarboxyl Pac = 4-Aminocinnamic acid Pal = β-(3-Pyridyl)alanine Pas = p-Aminosalicyloyl PBF = p-Bromophenylalanine Pcin = 4-Phenylcinnamoyl Pcn = α-Phenylcinnamoyl PCNF = p-Cyano-L-phenylalanine Pcnl = β-Phenylcinnamyl Pen(Mbzl) = S-(4-methylbenzyl)Penicillamine Pep = 1-(2-Phenylethyl)piperazine PFF = p-Fluorophenylalanine βPhc = β-Phenylcinnamoyl 3Php = 3-Phosphonopropionyl 5Phv = 5-Phenylvaleroyl Pic = Picolinoyl PIF = p-Iodophenylalanine Pipe = Piperidine Pipp = 4-Piperidinopiperidine Pipz = Piperazine Piva = Pivaloyl (Trimethylacetyl) Pmpz = 1-2-Pyrimidylpiperazine PNF = p-Nitro-phenylalanine Ppp = 1-(3-Phenylpropyl)piperazine Ppr = Phenylpropiolyl Ptmb = 4-(Trifluoromethyl)benzoyl αPtpa = α-(Phenylthio)phenylacetyl Pxa = Pyridoxamine [4-(aminomethyl)-5-hydroxy-6-methyl- 3-pyridinemethanol] Pya = trans-3-(3-Pyridyl)acryloyl Pypz = 1-2-Pyridylpiperazine Pyrc = Pyridine-3-carboxyl Pyz = Pyrazinoyl 3Qum = Quinoline-3-methyl 13cR = 13-cis-Retinoyl Ret = trans-Retinoyl Rio = Ricinoleyl Saa = trans-Styrylacetyl Sab = 4-Sulphamidobenzoyl cSdc = cis-Stilbene-4,4′-dicarboxylic Sibu = S-(+)-Ibuprofen CSsa = cis-Styrenesulphonylacetyl tβSts = trans-β-Styrenesulfonyl Taa = 1,2,4-Triazole-acetyl Tchc = (1R,3R,4S,5R)-1,3,4,5-Tetrahydrocyclohexane-1-carboxyl Tcpa = 2,4,5-Trichlorophenoxyacetyl Tf2c = trans-3,5-bis(Trifluoromethyl)cinnamoyl 4Tfmb = 4-(Trifluoromethoxy)benzoyl Thia = 3-(2-Thienyl)acryloyl Th2n = 1,2,3,4-Tetrahydro-2-naphthoyl Tic = Tetrahydroisoquinoline-3-carboxylic acid Tmb = Trimethoxybenzoyl Tmbp = 1-(2,4,6-Trimethylbenzyl)piperazine 4Tmbs = 4-(Trifluoromethoxy)benzenesulfonyl Tmbz = Trimethoxybenzyl Tmcc = 2,2,3,3-Tetramethylcyclopropanecarboxyl Tmpc = Carboxy-TEMPO: 4-carboxy-2,2,6,6- tetramethylpiperidinyloxy Tyr(Bzl) = O-Benzyl-tyrosine ZPcn = (Z)-α-Phenylcinnamoyl; (cis)

It will be appreciated by those skilled in the art that compounds of the invention having a chiral center may exist in, and be isolated in, optically active and racemic forms. Some compounds may exhibit polymorphism. It is to be understood that the present invention encompasses any racemic, optically-active, polymorphic, or stereoisomeric form, or mixtures thereof, of the anti-cancer compounds of the invention, it being well known in the art how to prepare optically active forms (for example, by resolution of the racemic form by recrystallization techniques, by synthesis from optically-active starting materials, by chiral synthesis, or by chromatographic separation using a chiral stationary phase) and how to determine anti-cancer and anti-tumor activity using the in vitro and in vivo tests described herein, or using other similar tests which are well known in the art.

Prodrugs of the compounds of Formula I may be identified using routine techniques known in the art. Various forms of prodrugs are known in the art. For examples of such prodrug derivatives, see, for example, a) Design of Prodrugs, edited by H. Bundgaard, (Elsevier, 1985) and Methods in Enzymology, Vol. 42, p. 309-396, edited by K. Widder, et al. (Academic Press, 1985); b) A Textbook of Drug Design and Development, edited by Krogsgaard-Larsen and H. Bundgaard, Chapter 5 “Design and Application of Prodrugs,” by H. Bundgaard p. 113-191 (1991); c) H. Bundgaard, Advanced Drug Delivery Reviews, 8, 1-38 (1992); d) H. Bundgaard, et al., Journal of Pharmaceutical Sciences, 77:285 (1988); and e) N. Kakeya, et al., Chem. Pharm. Bull., 32: 692 (1984), each of which is specifically incorporated herein by reference.

In addition, the invention also includes solvates, metabolites, and pharmaceutically acceptable salts of compounds of Formula I.

The term “solvate” refers to an aggregate of a molecule with one or more solvent molecules. A “metabolite” is a pharmacologically active product produced through in vivo metabolism in the body of a specified compound or salt thereof. Such products may result for example from the oxidation, reduction, hydrolysis, amidation, deamidation, esterification, deesterification, enzymatic cleavage, and the like, of the administered compound. Accordingly, the invention includes metabolites of compounds of Formula I, including compounds produced by a process comprising contacting a compound of this invention with a mammal for a period of time sufficient to yield a metabolic product thereof.

A “pharmaceutically acceptable salt” as used herein, includes salts that retain the biological effectiveness of the free acids and bases of the specified compound and that are not biologically or otherwise undesirable. A compound of the invention may possess a sufficiently acidic, a sufficiently basic, or both functional groups, and accordingly react with any of a number of inorganic or organic bases, and inorganic and organic acids, to form a pharmaceutically acceptable salt. Examples of pharmaceutically acceptable salts include those salts prepared by reaction of the compounds of the present invention with a mineral or organic acid or an inorganic base, such salts including sulfates, pyrosulfates, bisulfates, sulfites, bisulfites, phosphates, monohydrogenphosphates, dihydrogenphosphates, metaphosphates, pyrophosphates, chlorides, bromides, iodides, acetates, propionates, decanoates, caprylates, acrylates, formates, isobutyrates, caproates, heptanoates, propiolates, oxalates, malonates, succinates, suberates, sebacates, fumarates, maleates, butyn-1,4-dioates, hexyne-1,6-dioates, benzoates, chlorobenzoates, methylbenzoates, dinitromenzoates, hydroxybenzoates, methoxybenzoates, phthalates, sulfonates, xylenesulfonates, pheylacetates, phenylpropionates, phenylbutyrates, citrates, lactates, .gamma.-hydroxybutyrates, glycollates, tartrates, methanesulfonates, propanesulfonates, naphthalene-1-sulfonates, naphthalene-2-sulfonates, and mandelates. Since a single compound of the present invention may include more than one acidic or basic moieties, the compounds of the present invention may include mono, di or tri-salts in a single compound.

In the embodiments of the present invention in which the anti-cancer compound is a base, the desired pharmaceutically acceptable salt may be prepared by any suitable method available in the art, for example, treatment of the free base with an acidic compound, particularly an inorganic acid, such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like, or with an organic acid, such as acetic acid, maleic acid, succinic acid, mandelic acid, fumaric acid, malonic acid, pyruvic acid, oxalic acid, glycolic acid, salicylic acid, a pyranosidyl acid, such as glucuronic acid or galacturonic acid, an alphahydroxy acid, such as citric acid or tartaric acid, an amino acid, such as aspartic acid or glutamic acid, an aromatic acid, such as benzoic acid or cinnamic acid, a sulfonic acid, such as p-toluenesulfonic acid or ethanesulfonic acid, or the like.

In the embodiments of the present invention in which the anti-cancer compound is an acid, the desired pharmaceutically acceptable salt may be prepared by any suitable method, for example, treatment of the free acid with an inorganic or organic base. Preferred inorganic salts are those formed with alkali and alkaline earth metals such as lithium, sodium, potassium, barium and calcium. Preferred organic base salts include, for example, ammonium, dibenzylammonium, benzylammonium, 2-hydroxyethylammonium, bis(2-hydroxyethyl)ammonium, phenylethylbenzylamine, dibenzylethylenediamine, and the like. Other salts of acidic moieties may include, for example, those salts formed with procaine, quinine and N-methylglusoamine, plus salts formed with basic amino acids such as ornithine, histidine, lysine and arginine.

Whereas most of the results of in vivo anti-cancer activity of compounds reported in this application were obtained by intraperitoneal injection of compounds into nude mice bearing implanted tumors, reference compound M570 was shown to be active after oral administration.

The active anti-cancer compounds are effective over a wide dosage range and are generally administered in a therapeutically-effective amount. The dosage and manner of administration will be defined by the application of the anti-cancer agent and can be determined by routine methods of clinical testing to find the optimum dose. These doses are expected to be in the range of 0.001 mg/kg to 100 mg/kg of active compound. It will be understood, however, that the amount of the compound actually administered will be determined by a physician, in the light of the relevant circumstances, including the condition to be treated, the chosen route of administration, the actual compound administered, the age, weight, and response of the individual patient, the severity of the patient's symptoms, and the like.

When employed as pharmaceuticals, the compounds of Formula I are administered in the form of pharmaceutical compositions. These compounds can be administered by a variety of routes including oral, rectal, transdermal, subcutaneous, intravenous, intramuscular, and intranasal. Preferably, the anti-cancer compounds of the present invention are administered via intratracheal instillation or aerosol inhalation when used to treat lung cancer. Such pharmaceutical compositions are prepared in a manner well known in the pharmaceutical art and comprise at least one active anti-cancer compound of Formula I.

The pharmaceutical compositions of the present invention contain, as the active ingredient, one or more of the compounds of Formula I above, associated with pharmaceutically acceptable carriers. In making the compositions of this invention, the active ingredient is usually mixed with an excipient, diluted by an excipient or enclosed within such a carrier which can be in the form of a capsule, sachet, paper or other container. When the excipient serves as a diluent, it can be a solid, semi-solid, or liquid material, which acts as a vehicle, carrier or medium for the active ingredient. Thus, the compositions can be in the form of solutions, syrups, aerosols (as a solid or in a liquid medium), ointments containing, for example, up to 30% by weight of the active compound, soft and hard gelatin capsules, suppositories, sterile injectable solutions, and sterile packaged powders.

In preparing a formulation, it may be necessary to mill the anti-cancer compound to provide the appropriate particle size prior to combining with the other ingredients. If the anti-cancer compound is substantially insoluble, it ordinarily is milled to a particle size of less than 200 mesh. If the anti-cancer compound is substantially water soluble, the particle size is normally adjusted by milling to provide a substantially uniform distribution in the formulation, e.g. about 40 mesh.

Some examples of suitable excipients include lactose, dextrose, sucrose, sorbitol, mannitol, starches, gum acacia, calcium phosphate, alginates, tragacanth, gelatin, calcium silicate, microcrystalline cellulose, polyvinylpyrrolidone, cellulose, sterile water, syrup, and methyl cellulose. The formulations can additionally include: lubricating agents such as talc, magnesium stearate, and mineral oil; wetting agents; emulsifying and suspending agents; preserving agents such as methyl- and propylhydroxy-benzoates; sweetening agents; and flavoring agents. The compositions of the invention can be formulated so as to provide quick, sustained or delayed release of the active ingredient after administration to the patient by employing procedures known in the art.

For preparing solid compositions such as tablets, the principal active ingredient is mixed with a pharmaceutical excipient to form a solid preformulation composition containing a homogeneous mixture of a compound of the present invention. When referring to these preformulation compositions as homogeneous, it is meant that the active ingredient is dispersed evenly throughout the composition so that the composition may be readily subdivided into equally effective unit dosage forms such as tablets, pills and capsules. This solid preformulation is then subdivided into unit dosage forms of the type described above containing from, for example, 0.1 to about 500 mg of the active ingredient of the present invention.

The tablets or pills of the present invention may be coated or otherwise compounded to provide a dosage form affording the advantage of prolonged action. For example, the tablet or pill can comprise an inner dosage and an outer dosage component, the latter being in the form of an envelope over the former. The two components can be separated by an enteric layer which serves to resist disintegration in the stomach and permit the inner component to pass intact into the duodenum or to be delayed in release. A variety of materials can be used for such enteric layers or coatings, such materials including a number of polymeric acids and mixtures of polymeric acids with such materials as shellac, cetyl alcohol, and cellulose acetate.

The liquid forms in which the novel compositions of the present invention may be incorporated for administration orally or by injection include aqueous solutions suitably flavored syrups, aqueous or oil suspensions, and flavored emulsions with edible oils such as cottonseed oil, sesame oil, coconut oil, or peanut oil, as well as elixirs and similar pharmaceutical vehicles.

Compositions for inhalation or insufflation include solutions and suspensions in pharmaceutically acceptable, aqueous or organic solvents, or mixtures thereof, and powders. The liquid or solid compositions may contain suitable pharmaceutically acceptable excipients as described supra. Preferably these compositions are administered by the oral or nasal respiratory route for local or systemic effect. Compositions in preferably pharmaceutically acceptable solvents may be nebulized by use of inert gases. Nebulized solutions may be breathed directly from the nebulizing device or the nebulizing device may be attached to a face mask tent, or intermittent positive pressure breathing machine. Solution, suspension, or powder compositions may be administered, preferably orally or nasally, from devices which deliver the formulation in an appropriate manner.

Additional objects, advantages, and novel features of this invention will become apparent to those skilled in the art upon examination of the following examples thereof, which are not intended to be limiting.

EXAMPLES Example I Synthesis of Compounds

Compounds were synthesized by standard organic chemistry procedures well known in the art. Compounds were purified by HPLC and were characterized by analytical HPLC, TLC, and LDMS. Examples of structures of compounds tested are given in Tables 2 and 3.

Example II Synthesis of M570 Hydrochloride: F5c-OC2Y-Atmp.HCl

4-Amino-2,2,6,6-tetramethylpiperidine (Aldrich) was coupled with Boc-(O-2,6-dichlorobenzyl)-tyrosine, using BOP in DMF solution. The Boc protecting group was removed by TFA and the product coupled with 2,3,4,5,6-pentafluorocinnamic acid in DMF, using BOP in the presence of excess DIEA at room temperature for 3 hours. The DMF was removed in vacuo, the product was extracted into ethyl acetate and the solvent was evaporated. The residue was treated with 0.1-1.0 N HCl or 20% ethanolic HCl. The solvent was removed by evaporation in vacuo at room temperature. The residue was lyophilized from water-dioxane or crystallized from ethanol-ether.

Example III In Vitro Colorimetric Assay for Cell Survival

Cell growth and survival were measured by a rapid colorimetric assay based on the tetrazolium salt MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) (Mosmann, J. Immunol. Methods 65: 55-63, 1983, with minor modifications). Briefly, 1,000 normal lung fibroblasts or normal epithelial BEAS-2B cells, 1,000 or 5,000 viable non-SCLC cells or 10,000 viable SCLC cells were plated in 100 μL of growth medium in 96-well flat-bottomed microtiter plates. Cells were incubated overnight to allow recovery. Compounds to be tested were added to the cells in triplicate in a range of concentrations and the cells were incubated at 37° C., 5% CO₂, with 100% humidity. Control cells were treated in the same way without antagonists. All wells had a final volume of 200 μL. Plates were incubated for 4 days, allowing sufficient time for cell replication and compound-induced cell death to occur. On day 5, 25 μL of a 2 mg/mL solution of MTT (Sigma) dissolved in RMPI-1640 was added to each well. The plate was incubated for 4 h at 37° C. The supernatant liquid was removed and the blue formazan complex was dissolved by adding 100 μL of 0.02 N HCl in 75% isopropanol to all wells. Absorbance was immediately determined using a scanning multiwell plate reader. M570 caused 50% cell death at a concentration of 0.15 μM under these conditions. Examples of structures of compounds tested and their biological activities on cancers in vitro are given in Tables 2 and 3.

Example IV Inhibition of Tumor Growth in vivo in Nude Mice

Compounds having high in vitro cytotoxic activity were tested against implanted tumors in vivo. Athymic nude mice were implanted subcutaneously with suspensions (2 million SHP-77 SCLC cells, 1 million A549 NSCLC cells or 1.5 million PC3 PC cells) in Matrigel suspension. On the eighth day after tumor implantation groups of 5 mice bearing implants were injected intraperitoneally with the compounds being tested at 5 mg/kg/every second day or at 10 mg/kg/every fourth day; control animals were injected with an equal volume of isotonic saline. Less soluble compounds were initially dissolved in dimethyl sulfoxide (DMSO) and diluted with medium. In those cases the control injections contained the same concentration of DMSO. Tumor size was measured with a caliper three times per week. Tumor volume was calculated by the formula: Volume(cc)=3.14×(length)×(width)²/6 At autopsy tumors were removed and weighed. Tumor inhibition was calculated on both weight and measurement basis. Results of representative in vivo tests are given in Tables 2 and 3.In each Table, an IC50 value of “0” represents no detectable anti-cancer activity for a drug in a given cell line and “Stim.” indicates the observation of a stimulatory activity on the growth of the cancer cell line. For comparison, reference compound M570 caused 85% inhibition of growth of the SCLC line SHP-77 and 65% inhibition of PC cell line PC3 tumors at a dose of 5 mg/kg/every second day or at 10 mg/kg/every fourth day.

TABLE 2 Structures and Activities of Anti-Cancer Compounds of the Present Invention SHP-77 SHP-77 A-549 PC3 Analog In vitro In vivo In vivo In vivo Number Structure IC50, μM^(a) % inhib.^(c) % inhib.^(c) % inhib.^(c) M-1052 F5c-Igl-Atmp 7.3 27 M-1054 F5c-F5F-Atmp 4.6 47 M-1080 F5c-OBPY-Atmp 0 M-1092 F5BS-OC2Y-Atmp 14 Stim. M-1094 F5PT-OC2Y-Atmp 3.2 52 M-1096 #1 IMP-OC2Y-Atmp 7.0 M-1096 #2 IMP-OC2Y-Atmp 4.0 M-1098 #1 CHFB-OC2Y-Atmp 0 M-1098 #2 CHFB-OC2Y-Atmp 6.8 M-1100 Gun-Cys-OC2Y-Matp 13 13 M-1108 F5c-D-OC2Y-Atmp 0 46 M-1110 F5c-PCNF-Atmp 0.9 54 M-1112 F5c-PNF-Atmp 30 24 M-1114 F5c-Trp-Atmp 0 28 M-1116 Dca-OC2Y-Atmp 7.5 19 M-1118 F5c-OC2Y-Atmp(2Me) 1.8 M-1120 Glu-Trp-Atmp 0 M-1124 #1 Chpa-OC2Y-Atmp 1.7 50 Stim M-1124 #2 Chpa-OC2Y-Atmp 3.5 4.5 M-1126 22Dp-OC2Y-Atmp 4.0 36 M-1128 Rio-OC2Y-Atmp 1.6 48 44 M-1140 F5c-PFF-Atmp 15 M-1142 F5c-PIF-Atmp 7.2 M-1144 F5c-PBF-Atmp 7.2 20 M-1146 F5c-F3MF-Atmp 12 M-1148 F5c-NMF-Atmp 15.5 M-1150 F5c-Dip-Atmp 5 M-1152 3-Fa-PFF-Atmp 0 M-1154 2-Fa-PFF-Atmp 0 Stim M-1156 F5c-PFF-Abzp 7.5 56 M-1158 F5c-PFF-Mpz 28 M-1160 F5c-PFF-Dmpz 24 M-1162 F5c-PFF-Pmpz 15 M-1164 F5c-PFF-Pypz 14 M-1174 F5c-Bip-Atmp 3.7 57 37 M-1176 F5c-hPhe-Atmp 14 M-1178 F5c-Phe-Atmp 15 M-1180 F5c-PIF-Abzp 3.2 23 53 M-1182 F5c-F5F-Abzp 19.5 M-1186 F5c-F5F-Dmpz 11 M-1188 Bcpa-F5F-Abzp 4.5 17 M-1200 F5c-Nal-Dpic 5.0 Stim M-1202 F5c-PFF-Cbp 30 M-1204 Pya-Nal-Cbp 7.5 M-1208 F5c-PFF-Cpp 30 M-1212 Pya-PFF-Cpp 10 M-1214 Bcpa-Nal-Dpic 7.3 24 37 M-1216 F5c-Nal-Pypz 0 32 22 M-1218 F5c-Aic-Dpic 14 M-1242 Bcpa-Nal-Pypz 0 19 36 M-1244 Bcpa-Bip-Atmp 1.3 59 M-1246 Bcpa-Nal-Pipp 3.6 Stim M-1248 F5c-PIF-Pypz 13 M-1250 F5c-Nal-Pipp 7.6 M-1252 Tf2c-PIF-Pypz 0 M-1254 F5c-PIF-Dmpz 10 M-1256 F5c-PIF-Dpic 13 M-1258 F5c-Bip-Pypz 48 10 M-1260 F5c-Bip-Pmpz 10 60 M-1268 F5c-Bip-Bdbh 3 36

TABLE 3 Structures and Activities of Anti-Cancer Compounds of the Present Invention NSCLC SCLC SHP-77 A-549 PC3 Analog A-549 SHP-77 In vivo In vivo In vivo Number Structure IC50, μM^(b) IC50, μM^(a) % inhib.^(c) % inhib.^(c) % inhib.^(c) M-1272 F5c-Bip-Fpdh 22 10 71 M-1274 Bcpa-Bip-Atmp 7.3 2.1 M-1276 Bcpa-Bip-Bdbh 20 0 56 M-1278 F5c-Bip-Aqu M-1280 F5c-PIF-Bdbh 20 10 40 M-1284 F5c-PIF-Dasd 20 22 Stim. M-1286 F5c-PIF-(R)-(+)-Aqu 9.0 4.3 M-1288 F5c-Bip-(R)-(+)-Aqu 7.3 4.3 M-1290 F5c-PIF-(S)-(−)-Aqu 14 M-1292 F5c-Bip-(S)-(−)-Aqu 9.8 M-1294 F5c-PIF-Bhp 22 44 M-1296 F5c-Bip-Bhp M-1298 F5c-PIF-Cpp 21 M-1300 F5c-PIF-Cbp 21 M-1304 F5c-PIF-Pep 17 M-1306 F5c-PIF-3-Abzp 18 M-1308 F5c-PIF-Ppp 14 M-1310 F5c-PIF-4-Clbp 12 Stim. M-1312 F5c-PIF-BapS 13 33 M-1314 F5c-PIF-Chmp 21 M-1316 F5c-PIF-Alp 20 M-1318 F5c-PIF-Daep 8.4 M-1320 F5c-PIF-4-Cypp 17 M-1322 F5c-PIF-Fbp 13 46 M-1324 F5c-PIF-Chep 15 44 M-1326 F5c-PIF-BapR 10 0.6 M-1328 F5c-PIF-2-Cypp 14 M-1330 F5c-PIF-Ocp 17 40 M-1332 F5c-PIF-4-Mbp 7.8 63 M-1334 F5c-PIF-Tmbp 19 50 M-1336 F5c-PIF-Fpmp 12 71 M-1342 F5c-PIF-Fbhp M-1350 Pic-OC2Y-Atmp 6.1 36 M-1352 Pic-PCNF-Atmp 0 21 M-1354 Pic-Igl-Atmp 0 M-1356 F5pa-OC2Y-Atmp 4.4 0 M-1358 F5po-OC2Y-Atmp 4.1 30 M-1360 F5bz-OC2Y-Atmp 4.1 Stim. M-1362 3,4Dmc-OC2Y-Atmp 4.0 21 M-1364 3Ibu-OC2Y-Atmp 7.2 50 9 M-1366 Dmo-OC2Y-Atmp 3.8 14 M-1368 2Pyz-OC2Y-Atmp 3.2 47 Stim. M-1372 Bbz-OC2Y-Atmp 0 64 M-1374 Bbz-Igl-Atmp 0 M-1376 Indo-OC2Y-Atmp 1.8 1.5 18 44 M-1378 Aspr-OC2Y-Atmp 3.5 2.9 9 Stim. M-1380 Napr-OC2Y-Atmp 1.6 1.7 26 M-1382 Dfc-OC2Y-Atmp 2.9 46 M-1384 Chl-OC2Y-Atmp 1.9 1.8 46 Stim. M-1386 Tmpc-OC2Y-Atmp 12 20 M-1388 F3c-OC2Y-Atmp 1.6 21 Stim. M-1390 Gbz-OC2Y-Atmp 4.3 >40 Stim. M-1392 Ktpf-OC2Y-Atmp 2.9 28 18 M-1394 Ktlc-OC2Y-Atmp 4.9 2.9 68 Stim. M-1396 Dhq-OC2Y-Atmp 15 9 M-1398 Ppr-OC2Y-Atmp 8.0 65 M-1400 Pcn-OC2Y-Atmp 1.3 Stim. M-1402 Hcn-OC2Y-Atmp 0 Stim. M-1406 Tmcc-OC2Y-Atmp 5.3 25 M-1408 3,4,5Tmb-OC2Y-Atmp 8.0 Stim. M-1412 2Octe-OC2Y-Atmp 12 38 M-1414 34Mdc-OC2Y-Atmp 7.1 Stim. M-1416 Tchc-OC2Y-Atmp 0 0 M-1418 Thia-OC2Y-Atmp 8.6 9 M-1420 Atfb-OC2Y-Atmp 12 Stim. M-1422 Cpcpc-OC2Y-Atmp 13 31 M-1430 F5c-Pen(Mbzl)-Atmp 6.1 50 M-1432 F5c-PFF-Dmmp 18 M-1434 3Pal-OC2Y-Atmp 3.8 Stim. M-1436 Biot-OC2Y-Atmp 0 M-1440 Th2n-OC2Y-Atmp 3.5 15 M-1442 Arac-OC2Y-Atmp 6.4 31 M-1444 Tf2c-OC2Y-Atmp 1.4 11 M-1446 Ret-OC2Y-Atmp 6.7 60 M-1448 2Ina-OC2Y-Atmp 13 11 M-1450 2Hyb-OC2Y-Atmp 13 Stim. M-1452 Atfb-OC2Y-Atmp 7.2 Stim. M-1456 Fcin-OC2Y-Atmp 4.0 17 M-1458 Sab-OC2Y-Atmp 0 Stim. M-1460 Bcin-OC2Y-Atmp 23 38 M-1462 Hor-OC2Y-Atmp 0 7 M-1464 Aba-OC2Y-Atmp 14 14 M-1466 Biot-PCNF-Atmp 0 29 M-1468 Biot-Pen(Mbzl)-Atmp 0 46 M-1470 Ret-Pen(Mbzl)-Atmp M-1472 Ret-PCNF-Atmp M-1474 3Ibu-Pen(Mbzl)-Atmp 7.8 Stim. M-1476 3Ibu-PCNF-Atmp 0 M-1478 Rio-PCNF-Atmp 14 M-1480 Tmpc-Pen(Mbzl)-Atmp 0 Stim. M-1482 Tmpc-PCNF-Atmp 0 M-1484 Ptmb-OC2Y-Atmp 1.8 Stim. M-1486 F5po-Pen(Mbzl)-Atmp 4.2 21 M-1488 F5po-PCNF-Atmp 0 M-1490 F5bz-PCNF-Atmp >60 M-1492 Aca-Pen(Mbzl)-Atmp 3.4 15 M-1494 Aca-OC2Y-Atmp 1.6 40 M-1496 Aca-PCNF-Atmp >60 2 M-1498 Chl-Pen(Mbzl)-Atmp 3.5 20 M-1500 Chl-PCNF-Atmp 25 M-1502 F3c-Pen(Mbzl)-Atmp 3.4 11 M-1504 F3c-PCNF-Atmp >60 M-1506 Napr-Pen(Mbzl)-Atmp 4.7 13 M-1508 Napr-PCNF-Atmp 23 45 M-1510 22Dp-Pen(Mbzl)-Atmp 4.2 Stim. M-1512 22Dp-PCNF-Atmp 22 48 M-1514 Dca-Pen(Mbzl)-Atmp 7.3 M-1516 Dca-PCNF-Atmp 11 M-1518 Indo-Pen(Mbzl)-Atmp 6.0 Stim. M-1520 Indo-PCNF-Atmp 13 Stim. M-1522 2Pyz-Pen(Mbzl)-Atmp 31 Stim. M-1524 2Pyz-PCNF-Atmp >60 M-1528 Fmpi-OC2Y-Atmp 1.7 M-1532 Esul-OC2Y-Atmp 5 4.0 54 42 M-1536 4Tmbs-OC2Y-Atmp 3.2 Stim. M-1538 4Tfmb-OC2Y-Atmp 1.8 Stim. M-1542 4Bpc-OC2Y-Atmp 6.4 Stim. M-1544 F5c-OC2Y-(R)-Aqu 6.0 28 M-1546 F5c-OC2Y-(S)-Aqu 1.8 29 M-1548 #1 Chpa-OC2Y-(R)-Aqu 4.0 M-1548 #2 Chpa-OC2Y-(R)-Aqu 13 M-1550 #1 Chpa-OC2Y-(S)-Aqu 2.5 36 M-1550 #2 Chpa-OC2Y-(S)-Aqu 4.0 Stim. M-1552 F5c-OC2Y-Abzp 13 52 M-1554 F5c-OC2Y-Pmpz 6.8 Stim. M-1556 F5c-OC2Y-cDmbp 18 59 M-1558 Indo-OC2Y-Abzp 9.6 Stim. M-1560 Indo-OC2Y-cDmbp 0 Stim. M-1562 Indo-OC2Y-Pmpz 0 2 M-1564 F5c-OC2Y-tCip 4.0 M-1566 Indo-OC2Y-tCip 0 57 M-1568 Cmioc-OC2Y-Atmp 3.6 Stim. M-1574 Dbhc-OC2Y-Atmp 1.6 Stim. M-1576 Bzac-OC2Y-Atmp 6.2 57 M-1578 F5c-OC2Y-Dcpp Stim. M-1580 Indo-OC2Y-Dcpp M-1582 F5c-OC2Y-Amp 6.7 60 M-1584 Indo-OC2Y-Amp 1.5 32 M-1586 Indo-D-OC2Y-Atmp 1.7 38 M-1588 Indo-OC2Y-(R)-Aqu 3.9 8 M-1590 Indo-OC2Y-(S)-Aqu 4.1 Stim. M-1592 Pas-OC2Y-Atmp 7.2 Stim. M-1594 F5b-OC2Y-Atmp 3.1 20 M-1596 6Ani-OC2Y-Atmp 0 M-1598 tDecl-OC2Y-Atmp 4.1 M-1600 Pcnl-OC2Y-Atmp 4.1 44 M-1602 Acrc-OC2Y-Atmp 1.6 Stim. M-1604 3Qum-OC2Y-Atmp 7.4 Stim. M-1606 F5c-OC2Y-Bhp 17 M-1608 F5c-ObrZY-Atmp 10 29 M-1610 B6-OC2Y-Atmp 0 Stim. M-1612 B6P-OC2Y-Atmp 0 Stim. M-1614 F5c-OC2Y-cDmap 2.0 54 M-1616 3Php-OC2Y-Atmp 0 18 M-1618 Aq2c-OC2Y-Atmp 2.2 10 M-1622 F5c-OC2Y-Pxa 22 58 M-1624 F5c-OC2Y-Ambi 50 68 M-1628 Amts-OC2Y-Atmp 45 M-1630 Otac-OC2Y-Atmp 60 71 M-1632 F5c-OC2Y-Aem 7.8 32 M-1634 F5b-OC2Y-tCip 0 Stim. M-1636 F5c-OC2Y-Pipz M-1638 Chc-OC2Y-Atmp 18 39 M-1642 F5c-OC2Y-Apia 42 M-1648 Pac-OC2Y-Atmp 7.6 28 M-1650 Nba-OC2Y-Atmp 4.3 40 M-1652 2Ccn-OC2Y-Atmp 4.1 M-1654 Pcn-OC2Y-tCip 0 M-1656 Biot-OC2Y-tCip 5.5 M-1658 Pcn-OC2Y-Amp 10 M-1660 Pcn-OC2Y-Abzp 31 M-1662 Pcn-OC2Y-cDmbp 20 M-1664 Ktlc-OC2Y-cDmbp 0 M-1666 Ktlc-OC2Y-tCip 0 M-1668 Ktlc-OC2Y-Abzp 4.6 M-1670 Pcn-OC2Y-Pmpz 50 M-1672 Aaa-OC2Y-Pmpz >50 M-1674 Ktlc-OC2Y-Amp 3.2 M-1676 Aca-OC2Y-Amp 6.2 M-1678 Aca-OC2Y-Abzp 7.8 M-1680 Aca-OC2Y-Pmpz 33. M-1682 Pcn-D-OC2Y-Atmp 1.8 M-1684 Pcn-Igl-Atmp 4.2 M-1686 Ktlc-Igl-Atmp 14 M-1688 Indo-Igl-Atmp 4.0 M-1690 F5c-Igl-Pipz(F5b) 25 M-1692 Dcla-OC2Y-Atmp 7.2 M-1698 Dbhc-OC2Y-Amp 4.2 M-1700 Acrc-OC2Y-Amp 7.3 M-1702 Aq2c-OC2Y-Amp 3.6 M-1704 Pyrc-OC2Y-Atmp 25 M-1706 1Nap-OC2Y-Atmp 4.2 M-1708 1Nala-OC2Y-Atmp 7.2 M-1710 2Nala-OC2Y-Atmp 1.7 M-1712 5Phv-OC2Y-Atmp M-1714 2Cln-OC2Y-Atmp 4.0 M-1716 Hmqc-OC2Y-Atmp 7.2 M-1718 Baaa-OC2Y-Atmp 0 M-1720 Tcpa-OC2Y-Atmp M-1722 F5c-OC2Y-Pipe(Btmb) 26 M-1724 Pcn-OC2Y-Pipe(Btmb) 0 M-1726 F5c-OC2Y-Pipz(Tmbz) 26 M-1728 Pcn-OC2Y-Pipz(Tmbz) 26 M-1730 F5c-F5F-Pipz(F5b) 21 M-1732 F5c-OC2Y-Pipz(F5b) 24 M-1734 Pcn-OC2Y-Pipz(F5b) 24 M-1736 Piva-OC2Y-Atmp 13 M-1738 F5c-OC2Y-Apyr(Tmbz) 24 M-1742 Otac-OC2Y-Ambi M-1744 Mcoa-OC2Y-Atmp 7.1 M-1746 Chbu-OC2Y-Atmp 1.6 M-1748 tBua-OC2Y-Atmp 7.1 M-1750 (S)-MTPA-OC2Y-Atmp 4.2 M-1752 (R)-MTPA-OC2Y-Atmp 4.0 M-1754 Bcpa-OC2Y-Atmp 1.5 M-1756 Bcpoa-OC2Y-Atmp M-1758 αMcn-OC2Y-Atmp M-1760 Pcn-OCIY-Atmp 2.0 M-1762 Bcpa-OCIY-Atmp 3.0 M-1764 Pcn-Bip-Atmp 2.5 M-1766 Bcpoa-Bip-Atmp 2.0 M-1770 Pcn-Tic-Atmp 5.4 M-1772 Pcn-Tyr(Bzl)-Atmp M-1774 13cR-OC2Y-Atmp M-1776 Pcin-OC2Y-Atmp 1.4 M-1778 Mca-OC2Y-Atmp 1.5 M-1780 Saa-OC2Y-Atmp 1.8 M-1782 Bipa-OC2Y-Atmp 3.0 M-1786 Taa-OC2Y-Atmp 0 M-1788 Pcn-PFF-Atmp 2.3 M-1790 Pcn-F3MF-Atmp 2.2 M-1796 Bipa-Bip-Atmp 1.5 M-1798 Fmoc-Leu-Atmp 7.6 M-1800 Fmoc-OC2Y-Atmp 1.7 M-1804 Pcn-MC2Y-Atmp M-1806 αPtpa-OC2Y-Atmp M-1808 cSsa-OC2Y-Atmp M-1810 1Nac-OC2Y-Atmp M-1812 cSdc-OC2Y-Atmp M-1816 Bcpa-Dip-Atmp M-1832 3Iac-Bip-Atmp M-1834 F5c-OC2Y-AtmpO M-1836 ZPcn-OC2Y-Atmp M-1838 tβSts-OC2Y-Atmp M-1840 βPhc-OC2Y-Atmp M-1842 αFcn-OC2Y-Atmp M-1844 Nif-OC2Y-Atmp M-1846 Nif-Bip-Atmp M-1848 SIbu-OC2Y-Atmp M-1850 SIbu-Bip-Atmp M-1852 Fmoc-Bip-Atmp M-1854 Bphs-OC2Y-Atmp M-1856 Bphs-Bip-Atmp M-1858 αFcn-Bip-Atmp M-1862 2Nac-OC2Y-Atmp M-1864 Bipa-F3MF-Atmp M-1868 Pcn-PIF-Atmp Footnotes: ^(a)ED₅₀ for killing of SCLC strain SHP-77 in vitro, μM. ^(b)ED₅₀ for killing of NSCLC strain A-549 in vitro, μM. ^(c)Percent inhibition of tumor growth in vivo in nude mice. PC3 is prostate cancer.

The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and the skill or knowledge of the relevant art, are within the scope of the present invention. The embodiment described hereinabove is further intended to explain the best mode known for practicing the invention and to enable others skilled in the art to utilize the invention in such, or other, embodiments and with various modifications required by the particular applications or uses of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art. 

1. An anti-cancer compound selected from the group consisting of: (−)-2-Oxo-4-thiazolidinecarboxyl-O-2,6-dichlorobenzyl tyrosine-4-amino-2,2,6,6-tetramethylpiperidine (Otac-OC2Y-Atmp); 9-Fluorenylmethoxycarbonyl-O-2,6-dichlorobenzyl tyrosine-4-amino-2,2,6,6-tetramethylpiperidine (Fmoc-OC2Y-Atmp); 2,3,4,5,6-Pentafluorocinnamoyl-O-2,6-dichlorobenzyl tyrosine-2-(Aminomethyl)benzimidazole (F5c-OC2Y-Ambi); and, 5-benzoyl-2,3dihydro-1H-pyrrolizine-1-carboxyl-O-2,6-dichlorobenzyl tyrosine-4-amino-2,2,6,6-tetramethylpiperidine (Ktlc-OC2Y-Atmp).
 2. A prodrug of the anti-cancer compound of claim
 1. 3. A pharmaceutically-acceptable salt of the anti-cancer compound of claim
 1. 4. A pharmaceutical composition comprising an anti-cancer compound of claim 1 and at least one of an excipient and a pharmaceutically-acceptable carrier. 